Sediment migration may be studied with the aid of fluorescent organic substances applied in a colloidal state to sand particles along with a binding material. The substances are excited by 3650 or 2537 A wave length ultraviolet light. Tracer material simulates the physical characteristics of the body of sediment in which it is dispersed. Tracer grains, except for their fluorescent properties are indistinguishable from untreated grains. The most useful fluorescent dyes belong in the class xanthenes. Binding materials are found in adhesive amino and acrylic resins. Tracers are available in a wide variety with regard to color and duration.